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Hans M. Knoll 
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D Articles: 2141 Schem.: 159 Pict.: 102 28.Apr.05 20:06 Count of Thanks: 29 |
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How the German Tuning -Indicator works? Especially in the Set Koerting "Noblese" Type 22322 http://www.radiomuseum.org/dsp_modell.cfm?model_id=54720 Modern Tuning Indicators from Type EM84 , EM80 and so on, have include two independent electronic Systems. One part is the Amplifier, the other the Indicator -section. The amplifier is a Triode. Regular the AGC (automatic gain control) from the Radio-Frequency part, is an negative Voltage depends from Signal- strength of receiving Signal, or in case Tape- recorder, the value of recording Signal. In all cases that is an negative DC- Voltage. This voltage is connected to the grid of the Triode, via an R/C -Combination (lowpass), to remove the AC what's superimpose on DC Signal in both cases (radio und Tape). This Signal control's the Triode and on the Working resistor on Anode circuit, performed by an Resistor from 100Kohm's to 1 Meg ohm, the Anode Voltage. This Voltage changes from low (without signal) to high (with Signal). In normal cases the Anode of the Triode is direct connected to the Indicator part.  This Part have the Target ( leuchtschirm) an grid to distribute the electrons homodyne on Screen or Target, and a electrode called "Steg" [S] or Ray control electrode. These electrode is direct connected with the Anode of Triode. When the Voltage on grid of the triode (AGC) goes up and down, the Anode Voltage and the Ray controlling Element goes also up and down and changed the Shadow angle on Screen on Target. This is the normal situation. Its also possible, to make the variation of the Ray controlling system Voltage extern, not from build in Triode. It is possible, that the low Anode current in this cases gives a good Performance, but Test on Tube-tester with higher current say "bad" . That's my long explanation . The Diode in this Koerting is used to generate an negative Voltage from the 6.3 Volt AC Heather Voltage, allow to make a delayed AGC Voltage for better Signal to Noise Ratio. Hans M. Knoll This article was edited 29.Apr.05 16:22 by Hans M. Knoll . |
Joe Sousa 
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USA Articles: 663 Schem.: 214 Pict.: 434 01.Jun.08 04:53 Count of Thanks: 30 |
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Dear Hans, thank you for taking the time to explain eye tube operation.
This article was edited 27.Jul.09 20:37 by Ernst Erb . |
| Joe Sousa
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USA Articles: 663 Schem.: 214 Pict.: 434 07.Jun.11 17:08 Count of Thanks: 15 |
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An alternative way to find the AudioXpress article about eye tubes is to use a seach engine with these keywords: "Precise dB measurements with eye tubes" Regards, -Joe p.s.:The 1MB file size of the article falls outside the maximum size of 200k for direct attachment in the forum. The inclusion of incidental ads in the original magazine pages with the article may also be objectionable for forum posting. |
| Michael Watterson
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IRL Articles: 1004 Schem.: 650 Pict.: 2497 08.Oct.11 16:00 Count of Thanks: 14 |
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See Related ArticlesImages of magic eye types How the "Tune-A-Lite" works The Russian Neon/Argon Bargraph IN-13 (there is a less sensitive IN-9) and History of Tuning Indicators Here is an overview of Vintage Electronic Indicator technology (not just "Magic Eyes" or "Tuning Indicators") This article was edited 11.Oct.11 22:45 by Michael Watterson . |
